Ternary
diamond-like semiconductors, such as CuInTe2, are known
to exhibit promising p-type thermoelectric performance.
However, the interplay between growth conditions, native defects,
and thermoelectric properties have limited their realization. First-principles
calculations of CuInTe2 indicate that the electronic properties
are controlled by three dominant defects: VCu, CuIn, and InCu. The combination of these low-energy defects
with significant elemental chemical potential phase space for CuInTe2 yields a broad phase width. To validate these calculations,
polycrystalline, bulk samples were prepared and characterized for
their structural and thermoelectric properties as a function of stoichiometry.
Collectively, the off-stoichiometric samples show a range of carrier
concentrations that span 5 orders of magnitude (1015 to
1019 h+ cm–3). Mobility of
the off-stoichiometric samples suggests that copper vacancies act
as strongly scattering point-defect sites, while the other native
defects scatter less strongly. Such vacancy scattering extends to
the thermal conductivity where a reduction in κL is
observed and contributes to enhanced thermoelectric performance. Understanding
and controlling the native defects in CuInTe2 provides
a route toward n-type dopability as well as rational optimization
of the p-type material.
Germanium telluride is a high performing thermoelectric material that additionally serves as a base for alloys such as GeTe-AgSbTe2 and GeTe-PbTe. Such performance motivates exploration of other GeTe alloys in...
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